Differentiating pulmonary metastasis from benign lung nodules in thyroid cancer patients using dual-energy CT parameters.

OBJECTIVES: To explore the importance of quantitative characteristics of dual-energy CT (DECT) between pulmonary metastasis and benign lung nodules in thyroid cancer. METHODS: In this retrospective study, we identified 63 patients from our institution's database with pathologically proven thyroid cancer who underwent DECT to assess pulmonary metastasis. Among these patients, 22 had 55 pulmonary metastases, and 41 had 97 benign nodules. If nodules showed increased iodine uptake on I-131 single-photon emission computed tomography-computed tomography or increased size in follow-up CT, they were considered metastatic. We compared the clinical findings and DECT parameters of both groups and performed a receiver operating characteristic analysis to evaluate the optimal cutoff values of the DECT parameters. RESULTS: Patients with metastases were significantly older than patients with benign nodules (p = 0.048). The DECT parameters of the metastatic nodules were significantly higher than those of the benign nodules (iodine concentration [IC], 5.61 ± 2.02 mg/mL vs. 1.61 ± 0.98 mg/mL; normalized IC [NIC], 0.60 ± 0.20 vs. 0.16 ± 0.11; NIC using pulmonary artery [NICPA], 0.60 ± 0.44 vs. 0.15 ± 0.11; slope of the spectral attenuation curves [λHU], 5.18 ± 2.54 vs. 2.12 ± 1.39; and Z-effective value [Zeff], 10.0 ± 0.94 vs. 8.79 ± 0.75; all p < 0.001). In the subgroup analysis according to nodule size, all DECT parameters of the metastatic nodules in all subgroups were significantly higher than those of the benign nodules (all p < 0.05). The cutoff values for IC, NIC, λHU, NICPA, and Zeff for diagnosing metastases were 3.10, 0.29, 3.57, 0.28, and 9.34, respectively (all p < 0.001). CONCLUSIONS: DECT parameters can help to differentiate metastatic and benign lung nodules in thyroid cancer. KEY POINTS: • DECT parameters can help to differentiate metastatic and benign lung nodules in patients with thyroid cancer. • DECT parameters showed a significant difference between benign lung nodules and lung metastases, even for nodules with diameters ≥ 3 mm and < 5 mm. • Among the DECT parameters, the highest diagnostic accuracy for differentiating pulmonary metastases from benign lung nodules was achieved with the NIC and IC, followed by the NICPA and λHU, and their cutoff values were 0.29, 3.10, 0.28, and 3.57, respectively.

Paravertebral Muscles as Indexes of Sarcopenia and Sarcopenic Obesity: Comparison With Imaging and Muscle Function Indexes and Impact on Cardiovascular and Metabolic Disorders.

OBJECTIVE. The objectives of this study were to propose the use of the cross-sectional area of paravertebral muscle (PMA) and the ratio of the PMA to the cross-sectional area of visceral fat (PVR) as new indexes of sarcopenia or sarcopenic obesity through comparison with existing indexes and to show the clinical associations of PMA and PVR with hypertension and diabetes. SUBJECTS AND METHODS. A total of 1270 participants (608 men and 662 women; mean [± SD] age, 63.57 ± 6.94 years) were recruited from a community-based population of elderly individuals. PMA and PVR were measured on single-slice abdominal CT images. Pearson correlation was used to evaluate the correlation of PMA and PVR with widely used imaging and muscle function indexes of sarcopenia and sarcopenic obesity. Tertile categories of PMA and PVR were evaluated to investigate associations with risks for hypertension and diabetes in men and women, by use of separate multivariable logistic regression models. RESULTS. PMA was correlated with the cross-sectional area of thigh muscle on CT, appendicular skeletal muscle mass (ASM) on dual-energy x-ray absorptiometry, height-adjusted ASM (calculated as ASM divided by the height in meters squared), and body mass index (BMI)-adjusted ASM (calculated as ASM divided by BMI) (p < .01). PMA was also correlated with hand grip strength and gait speeds (p < .01). PVR was correlated with height-adjusted ASM and BMI-adjusted ASM (p < .01). A high PVR significantly decreased the odds ratios for hypertension and diabetes in the unadjusted model and the model adjusted for age, smoking, and drinking status. The ratio of the cross-sectional area of thigh muscle to the cross-sectional area of visceral fat and the BMI-adjusted ASM produced results similar to those of PVR in terms of the odds ratios for hypertension and diabetes. CONCLUSION. Single-slice abdominal CT can supply PMA and visceral fat information together. PMA and PVR were found to be reliable indexes of sarcopenia and sarcopenic obesity. A high PVR was associated with low risks for hypertension and diabetes.

Could both intrinsic and extrinsic iodine be successfully suppressed on virtual non-contrast CT images for detecting thyroid calcification?

PURPOSE: Although virtual non-contrast (VNC) successfully removes iodinated contrast, uncertainty exists regarding the feasibility of VNC to suppress iodine for detecting thyroid calcification. Therefore, we evaluated whether both intrinsic and extrinsic iodine attenuation were suppressed on VNC images. MATERIAL AND METHODS: We enrolled 128 patients (male: female 17:111; age 48.0 ± 10.4 years) who underwent dual-layer dual-energy CT (DL-DECT) examination before their thyroid cancer surgeries. Two additional sets of VNC (VNCu, VNCc) images were retrospectively generated from their true unenhanced (TUE) and true contrast-enhanced (TCE) series. We compared CT attenuation values measured on the VNCu and VNCc images by drawing identical regions of interest encompassing thyroid parenchyma, then subjectively determined the concordance of calcification. RESULTS: Although CT attenuation discrepancies between the VNCu and VNCc were significant (2.0 ± 5.7HU, p < 0.001),61.7%, 89.1%, and 100.0% of all measurements were < 5HU, < 10HU, and < 15HU. Based on Bland-Altman analysis, the limits of agreement were - 9.2HU and 13.2HU, whereas the proportional differences were small for VNC images generated from both TUE and TCE images. There was no discordance between two VNC image sets in detecting thyroid calcification. CONCLUSIONS: VNC technique could be a feasible method to suppress both intrinsic and extrinsically administered iodine for detecting thyroid calcification.

[Peer Review of Teleradiology at a Teleradiology Clinic: Comparison of Unacceptable Diagnosis and Clinically Significant Discrepancy between Radiology Sections and Imaging Modalities]. / ì›ê²©íŒë ì˜ë£Œê¸°ê´€ì—ì„œ 시행한 ì›ê²©íŒë ì˜ 동료평가: ì„¸ë¶€ì „ê³µë¶„ì•¼ì™€ 촬영장비에 따른 íŒë ë¶ˆì¼ì¹˜ ì •ë„ì™€ 불일치 íŒë ì˜ ìž„ìƒì  의의 비교.

Purpose: The purpose of this study was to evaluate the rates of unacceptable diagnosis and clinically significant diagnostic discrepancy in radiology sections and imaging modalities through a peer review of teleradiology. Materials and Methods: Teleradiology peer reviews in a Korean teleradiology clinic in 2018 and 2019 were included. The peer review scores were classified as acceptable and unacceptable diagnoses and clinically insignificant and significant diagnostic discrepancy. The diagnostic discrepancy rates and clinical significance were compared among radiology sections and imaging modalities using the chi-square test. Results: Of 1312 peer reviews, 117 (8.9%) cases had unacceptable diagnoses. Of 462 diagnostic discrepancies, the clinically significant discrepancy was observed in 104 (21.6%) cases. In radiology sections, the unacceptable diagnosis was highest in the musculoskeletal section (21.4%) (p < 0.05), followed by the abdominal section (7.3%) and neuro section (1.3%) (p < 0.05). The proportion of significant discrepancy was higher in the chest section (32.7%) than in the musculoskeletal (19.5%) and abdominal sections (17.1%) (p < 0.05). Regarding modalities, the number of unacceptable diagnoses was higher with MRI (16.2%) than plain radiology (7.8%) (p < 0.05). There was no significant difference in significant discrepancy. Conclusion: Peer review provides the rates of unacceptable diagnosis and clinically significant discrepancy in teleradiology. These rates also differ with subspecialty and modality.

Obesity and muscle may have synergic effect more than independent effects on brain volume in community-based elderly.

OBJECTIVE: To evaluate the individual and combined effects of obesity and muscle mass on brain volume in a community-dwelling healthy older population. METHODS: One thousand two hundred nine participants (M:F = 574:635, mean age 63.6 ± 6.9 years) were included. The cross-sectional area of visceral fat (VF), the height-adjusted appendicular skeletal muscle mass (ASM/height2), and the ratio of thigh muscle to visceral fat (TM/VF) represented obesity, muscle mass, and their integrated value, respectively. Linear regression analysis was performed to establish associations between 215 brain compartment volumes and VF, ASM/height2, and TM/VF after adjusting for covariates. RESULTS: On regression analysis, TM/VF had a positive correlation to the volumes of temporal lobe and cerebellum. TM/VF was associated with volumes of 10 subcompartments. TM/VF was positively correlated with the volumes of left entorhinal cortex, right temporal pole and inferior temporal gyrus related to cognition (p < 0.05, respectively), and the volumes of cerebellum and right pallidum related to movement (p < 0.05, respectively). However, VF had a negative correlation to temporal lobe volume and ASM/height2 had no significant correlation to any of the brain lobes. VF and ASM/height2 were correlated with volumes of 5 subcompartments and one subcompartment, respectively, CONCLUSIONS: TM/VF reflects the integrated effect of obesity and muscle mass and is associated with the volume of more brain regions compared to indices of obesity or muscle mass alone. The positive effect of muscle mass and the negative effect of obesity change the volumes of brain regions related to cognition and movement which were not significantly affected by obesity or muscle mass alone. KEY POINTS: • If obesity and muscle mass were considered together, we could find more significant brain volume changes which were not found in obesity or muscle alone. • The ratio of thigh muscle to visceral fat was positively correlated with the volumes of entorhinal cortex, temporal pole, and inferior temporal gyrus related to cognition. • The ratio of thigh muscle to visceral fat was positively correlated with the volumes of cerebellum and pallidum related to movement.

Thyroid isthmus agenesis and its clinical significance in a large-scale multidetector CT-based study.

OBJECTIVE: The purpose of this study was to estimate the incidence and clinical significance of thyroid isthmus agenesis based on multi-detector CT imaging in a large-scale study. METHODS: Data from 1601 patients who underwent neck multi-detector CT at our institution from January 2015 to March 2016 were included in this retrospective study. The morphology of each patient's thyroid gland was evaluated. We classified thyroid isthmus agenesis into two subgroups according to the thickness of the medial margin: clear-cut type (>4 mm) or tapering-edge type (≤4 mm). Associated thyroid pathologies were also evaluated. RESULTS: Thyroid isthmus agenesis was present in 69 patients (41 males, 28 females), and its incidence was 4.77%. Eleven patients (0.76%) had the clear-cut type and 58 patients (4.01%) had the tapering-edge type. Papillary thyroid carcinoma was diagnosed in 4 patients (5.7% of isthmus agenesis patients). A total of 7 patients underwent thyroid function testing during the course of this study; 1 of these patients presented with borderline hyperthyroidism, and the remaining 6 were in a euthyroid state. The clear-cut type showed a statistically significant narrow gap and a high incidence of pyramidal lobes compared to the tapering-edge type. CONCLUSION: Thyroid isthmus agenesis is not a rare developmental anomaly of the thyroid gland on multi-detector CT. Based on the metastatic pathophysiology of differentiated thyroid cancer, more extended indications for lobectomy are expected in differentiated thyroid cancer patients with thyroid isthmus agenesis.

Correction to: Characteristics of residual lymph nodes after six months of antituberculous therapy in HIV-negative individuals with cervical tuberculous lymphadenitis.

After publication of the original article [1], we were notified that an author's name has been incorrectly spelled. Soon You Kwon's correct full name is Soon Young Kwon.

Characteristics of residual lymph nodes after six months of antituberculous therapy in HIV-negative individuals with cervical tuberculous lymphadenitis.

BACKGROUND: The therapeutic response of cervical tuberculous lymphadenitis (CTBL) may be delayed or paradoxical, with the frequent development of residual lymph nodes (LNs) during and after antituberculous treatment. We investigated the incidence of residual LNs and the clinical, radiological, microbiological, and pathologic responses of patients with CTBL after 6 months of antituberculous therapy. METHODS: The medical records of HIV-negative adult patients with CTBL diagnosed between July 2009 and December 2017 were analyzed. After 6 months of first-line antituberculous treatment, computed tomography (CT) scans were conducted to evaluate for residual LNs. Fine-needle aspiration biopsy (FNAB) was carried out if a patient presented with residual LNs > 10 mm in diameter with central necrosis, peripheral rim enhancement, or perinodal inflammation on CT scan. RESULTS: Residual LNs were detected in 35 of 157 patients who underwent follow-up CT scans and were more commonly observed in younger patients who completed the treatment (mean years ± standard deviation [SD]: 33 ± 13 vs. 44 ± 16, p < 0.001). The recurrence rate was approximately 5%, which was not significantly different in both groups. Among the 15 patients who underwent FNAB, 3 (30%) presented with granuloma, and 2 of 15 and 10 of 14 patients had positive AFB and TB PCR results, respectively. The TB culture results of 15 patients were negative. CONCLUSIONS: Residual LNs may still be observed after 6 months of antituberculous treatment. Although the radiologic and pathologic findings after treatment are still indicative of TB, not all residual LNs indicate recurrence or treatment failure. A six-month therapy may be sufficient for cervical tuberculous lymphadenitis.

Dual-energy CT iodine quantification for characterizing focal thyroid lesions.

BACKGROUND: To determine the usefulness of dual-energy CT (DECT) iodine quantification to classify the focal thyroid lesions. METHODS: We retrospectively enrolled a total of 76 cytopathologically confirmed focal thyroid lesions (mean size: 1.9 cm). After drawing a region of interest on the DECT-derived iodine maps, the obtained iodine concentration values of thyroid nodules (IC_N) and normalized IC_N were compared between 3 groups: papillary thyroid carcinoma (PTC), benign nodule, and cyst. RESULTS: From all lesions, 46, 17, and 13 were assigned to the PTC, benign nodule, and cyst groups. IC_N was the highest in the benign nodule, lower in the PTC, and the lowest in the cyst (median [interquartile range]: 4.3 [3.13-5.48], 3.15 [2.29-4.01], 0.60 [0.33-0.88], all P < .001). Similarly, the normalized IC_N values were all statistically different from each other (P < .05).The multi-class area under the curves using the optimal cutoff values were 0.931 for IC_N and 0.918, 0.920 for normalized IC, respectively. CONCLUSION: DECT iodine quantification could be helpful to classify the focal thyroid lesions.

Lifestyle-dependent brain change: a longitudinal cohort MRI study.

We investigated both independent and interconnected effects of 3 lifestyle factors on brain volume, measuring yearly changes using large-scale longitudinal magnetic resonance imaging, in middle-aged to older adults. We measured brain volumes in a cohort (n = 984, 49-79 years) from the Korean Genome and Epidemiology Study group, using baseline and follow-up estimates after 4 years. In our analysis, the accelerated brain atrophy in normal aging was observed across regions (e.g., brain tissue: -0.098 ± 0.01 mL/y, p < 0.001). An independent lifestyle-specific trend of brain atrophy across time was also evident in men, where smoking (p = 0.012) and physical activity (p = 0.014) showed the strongest association with the atrophy rate. Linear regression analysis of the interconnected effect revealed that brain atrophy is mitigated by intense physical activity in smoking males. Lifestyle factors did not show any significant effect on brain volume in women. These results provide important information regarding lifestyle factors that affect brain aging in mid-to-late adulthood. Our findings may aid in the identification of preventive measures against dementia.

Characterizing Intraorbital Optic Nerve Changes on Diffusion Tensor Imaging in Thyroid Eye Disease Before Dysthyroid Optic Neuropathy.

OBJECTIVE: The aim of this study was to determine whether the optic nerve is affected by thyroid eye disease (TED) before the development of dysthyroid optic neuropathy with diffusion-tensor imaging (DTI). METHODS: Twenty TED patients and 20 controls were included. The mean, axial, and radial diffusivities and fractional anisotropy (FA) value were measured at the optic nerves in DTI. Extraocular muscle diameters were measured on computed tomography. The diffusivities and FA of the optic nerves were compared between TED and controls and between active and inactive stages of TED. The correlations between these DTI parameters and the clinical features were determined. RESULTS: The mean, axial, and radial diffusivities were lower in TED compared with the controls (P < 0.05). In contrast, FA was higher in TED (P = 0.001). Radial diffusivity was lower in the active stage of TED than the inactive stage (P = 0.035). The FA was higher in the TED group than in the control group (P = 0.021) and was positively correlated with clinical activity score (r = 0.364, P = 0.021), modified NOSPECS score (r = 0.469, P = 0.002), and extraocular muscle thickness (r = 0.325, P = 0.041) in the TED group. Radial diffusivity was negatively correlated with modified NOSPECS score (r = -0.384, P = 0.014), and axial diffusivity was positively correlated with exophthalmos degree (r = 0.363, P = 0.025). CONCLUSIONS: The diffusivities and FA reflected changes in the optic nerve before dysthyroid optic neuropathy in TED. The FA, in particular, reflected TED activity and severity.

Vascular Pattern Analysis on Microvascular Sonography for Differentiation of Pleomorphic Adenomas and Warthin Tumors of Salivary Glands.

OBJECTIVES: Pleomorphic adenomas and Warthin tumors are the most common salivary gland tumors. It is important to differentiate between them because at least a partial parotidectomy is necessary for pleomorphic adenomas, whereas enucleation is sufficient for Warthin tumors. This study aimed to evaluate the usefulness of vascular pattern analysis using microvascular sonography to differentiate between the tumors. METHODS: Sixty-two patients with pathologically proven pleomorphic adenomas (n = 38) and Warthin tumors (n = 24) were included. For all tumors, grayscale, power Doppler, and microvascular sonographic examinations were performed. Differences in vascular patterns (vascular distribution and internal vascularity) on power Doppler and microvascular sonography as well as grayscale sonographic features (size, shape, border, echogenicity, heterogeneity, and cystic change) between pleomorphic adenomas and Warthin tumors were evaluated. A comparison of diagnostic performances of grayscale sonography with power Doppler sonography and grayscale sonography with microvascular sonography was performed. The level of interobserver agreement between 2 reviewers in diagnosing tumors was evaluated. RESULTS: No grayscale sonographic features showed a significant difference between the tumors. Vascular distributions and internal vascularity on power Doppler sonography (P = .01 and .002) and microvascular sonography (both P < .001) were all significantly different. The diagnostic accuracy of grayscale sonography with microvascular sonography (79.0%) was higher than that of grayscale sonography with power Doppler sonography (72.6%). This difference was significant according to the McNemar test (P = .004). Interobserver agreement was excellent in diagnosing tumors on both grayscale sonography with power Doppler sonography (κ = 0.83) and grayscale sonography with microvascular sonography (κ = 0.94). CONCLUSIONS: Vascular pattern analysis using microvascular sonography with other sonographic features is helpful for differentiating between pleomorphic adenomas and Warthin tumors.

Amyloid Burden in Obstructive Sleep Apnea.

To test the hypothesis that excessive amyloid deposition is a biological link between obstructive sleep apnea (OSA) and Alzheimer's disease, we determined whether OSA increases cerebral amyloid burden, relative to controls, using Pittsburgh Compound B (PiB) PET imaging. The subjects were adult participants (age 50-65 years) from the Korean Genome and Epidemiology Study. Polysomnography, brain MRI including 3D images, and a detailed neuro-cognitive function test battery were done in 2011-2012. Nineteen OSA subjects (Apnea-Hypopnea Index [AHI] ≥15/h, 21.2±5.1/h; age 58.5±4.1 years; 9 male) and 19 controls (AHI 1.8±1.3/h; age 58.5±4.2 years; 9 male) underwent 60-min dynamic 11C-PiB PET. All subjects were right-handed with normal cognitive function and brain MRI. Controls were matched by age, gender, education, and APOE genotype. A voxel-wise comparison of PiB-PET images between the two groups was performed after spatial and count normalization with cerebellar gray matter as a reference. Covariates included the status of sleep duration, hypertension, diabetes, body mass index, exercise, depressive mood, smoking, and alcohol drinking. Cortical thickness on 3D MRI was also measured and compared between the two groups. The OSA group showed a higher PiB deposition in the right posterior cingulate gyrus and right temporal cortex (corrected p < 0.05). There was no area of higher uptake in the control compared with OSA. Regional differences in cortical thickness were not significant. The study suggests that OSA accelerates amyloid deposition and may contribute to the development or progression of Alzheimer's disease.

Assessing the accuracy and reliability of ultrasonographic three-dimensional parathyroid volume measurement in a patient with secondary hyperparathyroidism: a comparison with the two-dimensional conventional method.

PURPOSE: The purpose of this study was to investigate the accuracy and reliability of the semi-automated ultrasonographic volume measurement tool, virtual organ computer-aided analysis (VOCAL), for measuring the volume of parathyroid glands. METHODS: Volume measurements for 40 parathyroid glands were performed in patients with secondary hyperparathyroidism caused by chronic renal failure. The volume of the parathyroid glands was measured twice by experienced radiologists by two-dimensional (2D) and three-dimensional (3D) methods using conventional sonograms and the VOCAL with 30°angle increments before parathyroidectomy. The specimen volume was also measured postoperatively. Intraclass correlation coefficients (ICCs) and the absolute percentage error were used for estimating the reproducibility and accuracy of the two different methods. RESULTS: The ICC value between two measurements of the 2D method and the 3D method was 0.956 and 0.999, respectively. The mean absolute percentage error of the 2D method and the 3D VOCAL technique was 29.56% and 5.78%, respectively. For accuracy and reliability, the plots of the 3D method showed a more compact distribution than those of the 2D method on the Bland-Altman graph. CONCLUSION: The rotational VOCAL method for measuring the parathyroid gland is more accurate and reliable than the conventional 2D measurement. This VOCAL method could be used as a more reliable follow-up imaging modality in a patient with hyperparathyroidism.

Fractional anisotropy and diffusivity changes in thyroid-associated orbitopathy.

INTRODUCTION: To investigate the extraocular muscle (EOM) changes in thyroid-associated orbitopathy (TAO) on DTI and the correlations between DTI parameters and clinical features. METHODS: Twenty TAO patients and 20 age- and sex-matched controls provided informed consent and were enrolled. Ten-directional DTI was acquired in orbit. Fractional anisotropy (FA), mean, axial, and radial diffusivities were obtained at medial and lateral EOMs in both orbits. EOM thickness was measured in patients using axial CT images. FA and diffusivities were compared between patients and controls. The relationships between DTI values and muscle thickness and exophthalmos were evaluated. DTI values compared between patients in active and inactive phases by clinical activity score of TAO. DTI values were also compared between acute and chronic stages by the duration of disease. RESULTS: In medial EOM, FA was significantly lower in patients (p < 0.001) and negatively correlated with muscle thickness (r = -0.604, p < 0.001). Radial diffusivity was significantly higher in patients (p = 0.010) and correlated with muscle thickness (r = 0.349, p = 0.027). In lateral EOM, DTI values did not differ between patients and controls. In the acute stage, the diffusivities of the medial rectus EOM were increased compared with the chronic stage. DTI values of the medial and lateral rectus EOM did not differ significantly between active and inactive phases. CONCLUSION: DTI can be used to diagnose TAO with FA and radial diffusivity change in EOM. Diffusivities can be used to differentiate acute and chronic stage of TAO. However, DTI values showed limitation in reflecting TAO activity according to the CAS.

Feasibility Study of a Contrast-Enhanced Multi-Detector CT (64 Channels) Protocol for Papillary Thyroid Carcinoma: The Influence of Different Scan Delays on Tumor Conspicuity.

BACKGROUND: Recently, a number of studies have advocated the diagnostic benefit of contrast-enhanced computed tomography (CECT) in the current ultrasound (US)-based preoperative evaluation of thyroid cancer. However, no study has been conducted to optimize a CECT protocol focusing on tumor conspicuity using a multi-detector CT scanner. This study aimed at determining the optimal scan delay for increased CT attenuation differences between thyroid cancer and parenchymal background using a biphasic CECT examination. METHODS: This study retrospectively enrolled 84 patients (M:F = 7:77; Mage = 44.8 ± 10.9 years) with 87 papillary thyroid carcinomas (Msize = 14.1 mm) who consecutively underwent US and CECT examination prior to surgery. In each patient, CT scanning was taken twice-once with a 40-second delay and once with a 70-second delay-using a 64-channel multi-detector scanner. After obtaining the mean attenuation value (MAV) of the thyroid cancer and the ipsilateral parenchyma by drawing regions of interest on the CECT images based on their cytopathologic results and US findings, the parenchyma-cancer differences (PCD) between the early and delayed scans were simply compared using a paired t-test. Then, the mean differences in the MAVs of the thyroid cancer and ipsilateral parenchyma (hereafter abbreviated as Group) between the early and delayed scans (abbreviated as Time) were compared after adjusting for the other factors that significantly affected MAVs, such as concentration of iodinated contrast medium (abbreviated as CCM) and size of thyroid cancer (abbreviated as Size) using a repeated-measures general linear model. RESULTS: Because the ipsilateral parenchyma exhibited significantly higher attenuation on the early scan and further decline on the delayed scan compared with thyroid cancer (p < 0.001), the PCD for thyroid cancer was significantly better with a 40-second scan delay than a 70-second delay (58.8 ± 36.6 Hounsfield units [HU] vs. 40.4 ± 25.6 HU; p < 0.001). Similar results were obtained from the repeated-measures general linear model that considered the effects of CCM, Size, Group, and Time, and the interaction of Group and Time. CONCLUSION: Based on this CECT study that adjusted for the effects of CCM and size on MAV, early scans (e.g., 40-second scan delay) are helpful for improving the tumor conspicuity of thyroid cancer on CECT images.

Comparison of Ultrasonographic Findings of Biopsy-Proven Tuberculous Lymphadenitis and Kikuchi Disease.

OBJECTIVE: Although tuberculous lymphadenitis and Kikuchi disease are common causes of cervical lymphadenopathy in Asians and exhibit similar clinical manifestations, their treatment strategies are totally different. The purpose of this study was to identify ultrasonographic features that distinguish these two diseases. MATERIALS AND METHODS: This study was approved by the Institutional Review Board. The study included 77 patients with tuberculous lymphadenitis and 135 patients with Kikuchi disease. The sex and age distributions of the patients were analyzed. The size and shape of lymph nodes (LNs), presence of conglomeration, increased perinodal echogenicity, echogenic hilum, posterior neck involvement, internal calcification, patterns of internal necrosis, laterality of involved LNs, and hilar vascular patterns on ultrasonography were compared between the two groups. Multiple logistic regression analysis was conducted to identify independent findings to discriminate tuberculous lymphadenitis from Kikuchi disease. Finally, diagnostic accuracies were calculated using the independent findings. RESULTS: The presence of an echogenic hilum, internal calcification, patterns of internal necrosis, and LN hilar vascular structures on power Doppler ultrasonography were independent findings that discriminated tuberculous lymphadenitis from Kikuchi disease. The diagnostic accuracy of each of these four factors was 84.9% (181/212), 76.9% (163/212), 84% (178/212), and 89.2% (189/212), respectively. A combination of internal calcification and hilar vascular structures showed the best accuracy of 89.6% (190/212) (sensitivity, 86.7% [117/135]; specificity, 94.8% [73/77]) for diagnosing Kikuchi disease. CONCLUSION: The presence of an echogenic hilum, internal calcification, pattern of internal necrosis, and LN hilar vascular structures are useful ultrasonographic findings to differentiate tuberculous lymphadenitis from Kikuchi disease.

Leptomeningeal enhancement on magnetic resonance imaging as a predictor of hemodynamic insufficiency.

OBJECTIVE: The objective of this study was to evaluate the value of leptomeningeal enhancement on magnetic resonance imaging in relation to relative cerebral blood flow (rCBF) and cerebrovascular reserve. METHODS: A retrospective analysis was performed for 31 patients with internal carotid artery or proximal middle cerebral artery occlusion without primary collateral flow, who underwent enhanced T1-weighted magnetic resonance imaging and acetazolamide-challenged perfusion computed tomography. They were graded into 3 groups in leptomeningeal enhancement on T1-weighted imaging. The rCBF and the percentage change of cerebral blood flow were obtained in the ipsilateral middle cerebral artery territory. RESULTS: The mean percentage changes of CBF were -13.7%, 6.9%, and 23.8% in prominent (n = 11), mild (n = 11), and equivalent (n = 9) increased enhancements, respectively. The degree of leptomeningeal enhancement was significantly reverse-correlated with percentage change of CBF (P < 0.001), whereas the rCBFs were not significantly different. CONCLUSIONS: The reverse correlation between leptomeningeal enhancement and cerebrovascular reserve suggests that increased enhancement may indicate impaired primary collaterals and hemodynamic insufficiency. Therefore, leptomeningeal enhancement degree can be used as an indicator of hemodynamic state in stroke.